If your New Year’s resolution to lose weight has you eyeing the natural weight loss pills at the drug store, look the other way.

Although we’ve heard much about the dangers of ephedra-containing diet pills, ephedra-free diet pills can be hazardous to your health as well. Ones that contain bitter orange, caffeine, or other natural stimulants may cause dangerous spikes in heart rate and blood pressure. Shed excess pounds with a sustainable program of healthy eating and exercise.

Vitamins and supplements are not regulated in the same way as medications. Just because they are available over-the-counter or claim to contain all-natural ingredients doesn’t mean that they are safe. The same is true of diet pills. While products containing the stimulant ephedra are now banned, weight-loss aids may contain other stimulants that increase the risk of heart attack and stroke by raising heart rate and blood pressure.

In a study comparing the effects of two weight-loss aids, participants who took one dose of a diet pill containing bitter orange (Citrus aurantium) experience an increase in heart rate of more that 11 beats per minute while people who took a diet pill containing bitter orange, caffeine, and other ingredients experienced an increase of almost 17 beats per minute as well as a rise in blood pressure.